On Jan. 14, the Iranian tanker Sanchi sank in the worst oil shipping disaster in decades, killing all 32 crew onboard. South Korean and Japanese officials believed that water contaminated by the cargo of toxic condensate oil and the ship’s fuel oil would not reach as far as Japan or South Korea. However, data from Britain’s National Oceanography Centre and the University of Southampton predicted the opposite.

Here we visualised ocean currents and simulated the projected spread of oil over three months. We also used environmental data and detailed fishing activity to highlight environmental concerns.

The projections did turn out to be reasonably accurate, with traces of oil washing up on over a dozen islands in southern Japan. The long-term damage to fisheries and marine life in the area remains to be seen.